Using the tensor renormalization group method based on the higher-order singular value decomposition, we have studied the phase transitions of the five-state clock model on the square lattice. The temperature dependen...Using the tensor renormalization group method based on the higher-order singular value decomposition, we have studied the phase transitions of the five-state clock model on the square lattice. The temperature dependence of the specific heat indicates the system has two phase transitions, as verified clearly by the correlation function at three representative temperatures. By calculating the magnetic susceptibility, we obtained only the upper critical temperature as T_(c2)= 0.9565(7).Investigating the fixed-point tensor, we precisely locate the transition temperatures at T_(c1)= 0.9029(1) and T_(c2)= 0.9520(1),consistent well with the Monte Carlo and the density matrix renormalization group results.展开更多
Reliable process monitoring is important for ensuring process safety and product quality.A production process is generally characterized bymultiple operation modes,and monitoring thesemultimodal processes is challengi...Reliable process monitoring is important for ensuring process safety and product quality.A production process is generally characterized bymultiple operation modes,and monitoring thesemultimodal processes is challenging.Most multimodal monitoring methods rely on the assumption that the modes are independent of each other,which may not be appropriate for practical application.This study proposes a transition-constrained Gaussian mixture model method for efficient multimodal process monitoring.This technique can reduce falsely and frequently occurring mode transitions by considering the time series information in the mode identification of historical and online data.This process enables the identified modes to reflect the stability of actual working conditions,improve mode identification accuracy,and enhance monitoring reliability in cases of mode overlap.Case studies on a numerical simulation example and simulation of the penicillin fermentation process are provided to verify the effectiveness of the proposed approach inmultimodal process monitoring with mode overlap.展开更多
In this study, the initial perturbations that are the easiest to trigger the Kuroshio Extension(KE) transition connecting a basic weak jet state and a strong, fairly stable meandering state, are investigated using a r...In this study, the initial perturbations that are the easiest to trigger the Kuroshio Extension(KE) transition connecting a basic weak jet state and a strong, fairly stable meandering state, are investigated using a reduced-gravity shallow water ocean model and the CNOP(Conditional Nonlinear Optimal Perturbation) approach. This kind of initial perturbation is called an optimal precursor(OPR). The spatial structures and evolutionary processes of the OPRs are analyzed in detail. The results show that most of the OPRs are in the form of negative sea surface height(SSH) anomalies mainly located in a narrow band region south of the KE jet, in basic agreement with altimetric observations. These negative SSH anomalies reduce the meridional SSH gradient within the KE, thus weakening the strength of the jet. The KE jet then becomes more convoluted, with a high-frequency and large-amplitude variability corresponding to a high eddy kinetic energy level; this gradually strengthens the KE jet through an inverse energy cascade. Eventually, the KE reaches a high-energy state characterized by two well defined and fairly stable anticyclonic meanders. Moreover, sensitivity experiments indicate that the spatial structures of the OPRs are not sensitive to the model parameters and to the optimization times used in the analysis.展开更多
<正> The transverse spin-2 Ising ferromagnetic model with a longitudinal crystal-field is studied within themean-field theory based on Bogoliubov inequality for the Gibbs free energy.The ground-state phase diagr...<正> The transverse spin-2 Ising ferromagnetic model with a longitudinal crystal-field is studied within themean-field theory based on Bogoliubov inequality for the Gibbs free energy.The ground-state phase diagram and thetricritical point are obtained in the transverse field Ω/zJ-longitudinal crystal D/zJ field plane.We find that there are thefirst order-order phase transitions in a very small range of D/zJ besides the usual first order-disorder phase transitionsand the second order-disorder phase transitions.展开更多
In the ISO9000"input-output"process model,the concept of process quality is difficult to get the correct interpretation. From the"white box"theory of process,this paper puts forward the scientific ...In the ISO9000"input-output"process model,the concept of process quality is difficult to get the correct interpretation. From the"white box"theory of process,this paper puts forward the scientific meaning of the concept of process quality and the process quality model by taking the basic operating unit of 6M1E in the railway construction project for example. The basic operating unit system consists of technological natural process,operation process and management process;the process quality of the basic operating unit system depends on the interrelation and interaction among those three sub-processes,and also subjects to the impact of the external disturbance input factors. Finally,the cast-in-situ prestressed concrete continuous box girder construction process is utilized to elaborate the specific application of this theory in the quality management of the railway construction project.展开更多
We investigate a simple evolutionary game model in one dimension. It is found that the system exhibits a discontinuous phase transition from a defection state to a cooperation state when the b payoff of a defector exp...We investigate a simple evolutionary game model in one dimension. It is found that the system exhibits a discontinuous phase transition from a defection state to a cooperation state when the b payoff of a defector exploiting a cooperator is small. Furthermore, if b is large enough, then the system exhibits two continuous phase transitions between two absorbing states and a coexistence state of cooperation and defection, respectively. The tri-critical point is roughly estimated. Moreover, it is found that the critical behavior of the continuous phase transition with an absorbing state is in the directed percolation universality class.展开更多
与传统列控系统相比,全自动无人驾驶运营场景更加复杂多变,潜在的危险及致因具有更强的隐蔽性和复杂性,给运营安全带来了新的挑战。针对以上问题,提出一种STAMP(Systems-Theoretic Accident Model and Process)与模型检验相结合的复杂...与传统列控系统相比,全自动无人驾驶运营场景更加复杂多变,潜在的危险及致因具有更强的隐蔽性和复杂性,给运营安全带来了新的挑战。针对以上问题,提出一种STAMP(Systems-Theoretic Accident Model and Process)与模型检验相结合的复杂运营场景安全验证方法。首先,基于STAMP理论构建运营场景分层控制结构模型,辨识潜在的不安全控制行为、分析危险致因和安全约束;其次,定义分层控制结构模型与安全状态机模型间的基本转换规则,基于分层控制结构模型、安全约束和转换规则,构建运营场景安全状态机模型;最后,针对提取的安全约束,利用数据流图建立安全属性验证模型,结合模型检验技术,对运营场景安全状态机模型进行形式化验证。以全自动无人驾驶运营场景中列车自动进站停车为例,对方法进行验证分析。结果表明,当STAMP理论提取的安全约束通过了场景安全状态机模型的验证时,表示在该场景中对应的不安全控制行为没有发生且不导致相应危险。该方法结合系统安全分析与形式化建模验证的优势,降低了运营场景建模的难度,构建的运营场景形式化模型满足系统安全约束,可以作为全自动无人驾驶系统安全设计和安全改进的重要基础。展开更多
摩擦力是影响直线伺服系统低速运行与点对点定位精度的主要非线性扰动。广义麦克斯韦(generalized Maxwellslip,GMS)摩擦模型虽然可以准确描述摩擦特性用于前馈补偿,但其存在切换点过渡时振荡的问题,同时易受测量噪声和摩擦参数变化等...摩擦力是影响直线伺服系统低速运行与点对点定位精度的主要非线性扰动。广义麦克斯韦(generalized Maxwellslip,GMS)摩擦模型虽然可以准确描述摩擦特性用于前馈补偿,但其存在切换点过渡时振荡的问题,同时易受测量噪声和摩擦参数变化等影响。为此,该文提出基于平滑GMS模型和改进扩张状态观测器(extended state observer,ESO)的复合摩擦补偿策略。首先,引入过渡用双曲正切函数以解决GMS模型中在切换点的反复穿越问题,并给出该模型的离线辨识方法。其次,设计基于模型信息的四阶ESO补偿剩余摩擦力与未知扰动,并引入切比雪夫滤波器整定观测器增益,以降低扰动观测与噪声敏感之间的冲突。为验证所提摩擦补偿策略的有效性,在小型高精度永磁同步直线电机定位平台上进行定位实验。实验结果验证了所提摩擦补偿策略的可行性和有效性。展开更多
A novel control strategy for a continuous stirred tank reactor(CSTR)system,which has the typical characteristic of strongly pronounced nonlinearity,multiple operating points,and a wide operating range,is initiated fro...A novel control strategy for a continuous stirred tank reactor(CSTR)system,which has the typical characteristic of strongly pronounced nonlinearity,multiple operating points,and a wide operating range,is initiated from the point of hybrid systems.The proposed scheme makes full use of the modeling power of mixed logical dy- namical(MLD)systems to describe the highly nonlinear dynamics and multiple operating points in a unified framework as a hybrid system,and takes advantage of the good control quality of model predictive control(MPC) to design a controller.Thus,this approach avoids oscillation during switching between sub-systems,helps to relieve shaking in transition,and augments the stability robustness of the whole system,and finally achieves optimal(i.e. fast and smooth)transition between operating points.The simulation results demonstrate that the presented ap- proach has a satisfactory performance.展开更多
The research hotspot in post-genomic era is from sequence to function. Building genetic regulatory network (GRN) can help to understand the regulatory mechanism between genes and the function of organisms. Probabilist...The research hotspot in post-genomic era is from sequence to function. Building genetic regulatory network (GRN) can help to understand the regulatory mechanism between genes and the function of organisms. Probabilistic GRN has been paid more attention recently. This paper discusses the Hidden Markov Model (HMM) approach served as a tool to build GRN. Different genes with similar expression levels are considered as different states during training HMM. The probable regulatory genes of target genes can be found out through the resulting states transition matrix and the determinate regulatory functions can be predicted using nonlinear regression algorithm. The experiments on artificial and real-life datasets show the effectiveness of HMM in building GRN.展开更多
The actual world model, the “Standard Model of Cosmology” (SMC), which dates back to the 1950s, no longer corresponds to the latest state of knowledge on the cosmos. By way of example, the assumption made in the SMC...The actual world model, the “Standard Model of Cosmology” (SMC), which dates back to the 1950s, no longer corresponds to the latest state of knowledge on the cosmos. By way of example, the assumption made in the SMC that the expansion of the cosmos is continually being reduced due to the effect of the gravitation exerted on all the matter in the universe is now contradicted by recent measurements. The reason for the expansion of cosmic space in accordance with Hubble’s Law is not physically explained by the SMC but merely stated as a fact. Another example is provided by the “dark phenomena”, which make up by far the greatest part of the energy of the cosmos, and exert a dominant influence on its behaviour. In spite of intensive research over the decades to provide answers to these as well as other open issues in cosmology, no satisfactory and plausible answers have hitherto been found. It is indeed time to propose an alternative cosmological world model to the SMC in the light of the latest insights on the universe.展开更多
基金Project supported by the Fundamental Research Funds for the Central Universities,China(Grant No.531107040857)the Natural Science Foundation of Hunan Province,China(Grant No.851204035)the National Natural Science Foundation of China(Grant No.11774420)
文摘Using the tensor renormalization group method based on the higher-order singular value decomposition, we have studied the phase transitions of the five-state clock model on the square lattice. The temperature dependence of the specific heat indicates the system has two phase transitions, as verified clearly by the correlation function at three representative temperatures. By calculating the magnetic susceptibility, we obtained only the upper critical temperature as T_(c2)= 0.9565(7).Investigating the fixed-point tensor, we precisely locate the transition temperatures at T_(c1)= 0.9029(1) and T_(c2)= 0.9520(1),consistent well with the Monte Carlo and the density matrix renormalization group results.
基金supported in part by National Natural Science Foundation of China under Grants 61973119 and 61603138in part by Shanghai Rising-Star Program under Grant 20QA1402600+1 种基金in part by the Open Funding from Shandong Key Laboratory of Big-data Driven Safety Control Technology for Complex Systems under Grant SKDN202001in part by the Programme of Introducing Talents of Discipline to Universities(the 111 Project)under Grant B17017.
文摘Reliable process monitoring is important for ensuring process safety and product quality.A production process is generally characterized bymultiple operation modes,and monitoring thesemultimodal processes is challenging.Most multimodal monitoring methods rely on the assumption that the modes are independent of each other,which may not be appropriate for practical application.This study proposes a transition-constrained Gaussian mixture model method for efficient multimodal process monitoring.This technique can reduce falsely and frequently occurring mode transitions by considering the time series information in the mode identification of historical and online data.This process enables the identified modes to reflect the stability of actual working conditions,improve mode identification accuracy,and enhance monitoring reliability in cases of mode overlap.Case studies on a numerical simulation example and simulation of the penicillin fermentation process are provided to verify the effectiveness of the proposed approach inmultimodal process monitoring with mode overlap.
基金supported by the National Natural Science Foundation of China (Grant Nos. 41576015, 41306023, 41490644 and 41490640)the Natural Science Foundation Of China (NSFC) Innovative Group (Grant No. 41421005)+1 种基金the NSFC–Shandong Joint Fund for Marine Science Research Centers (Grant No. U1406401)support from the University of Naples Parthenope (Grant No. DSTE315)
文摘In this study, the initial perturbations that are the easiest to trigger the Kuroshio Extension(KE) transition connecting a basic weak jet state and a strong, fairly stable meandering state, are investigated using a reduced-gravity shallow water ocean model and the CNOP(Conditional Nonlinear Optimal Perturbation) approach. This kind of initial perturbation is called an optimal precursor(OPR). The spatial structures and evolutionary processes of the OPRs are analyzed in detail. The results show that most of the OPRs are in the form of negative sea surface height(SSH) anomalies mainly located in a narrow band region south of the KE jet, in basic agreement with altimetric observations. These negative SSH anomalies reduce the meridional SSH gradient within the KE, thus weakening the strength of the jet. The KE jet then becomes more convoluted, with a high-frequency and large-amplitude variability corresponding to a high eddy kinetic energy level; this gradually strengthens the KE jet through an inverse energy cascade. Eventually, the KE reaches a high-energy state characterized by two well defined and fairly stable anticyclonic meanders. Moreover, sensitivity experiments indicate that the spatial structures of the OPRs are not sensitive to the model parameters and to the optimization times used in the analysis.
文摘<正> The transverse spin-2 Ising ferromagnetic model with a longitudinal crystal-field is studied within themean-field theory based on Bogoliubov inequality for the Gibbs free energy.The ground-state phase diagram and thetricritical point are obtained in the transverse field Ω/zJ-longitudinal crystal D/zJ field plane.We find that there are thefirst order-order phase transitions in a very small range of D/zJ besides the usual first order-disorder phase transitionsand the second order-disorder phase transitions.
基金Key Subject of Ministry of Railway Technology Research and Development Program(No.2011G010-D)Central University Funds for Basic Research(No.SWJTU12ZT12)
文摘In the ISO9000"input-output"process model,the concept of process quality is difficult to get the correct interpretation. From the"white box"theory of process,this paper puts forward the scientific meaning of the concept of process quality and the process quality model by taking the basic operating unit of 6M1E in the railway construction project for example. The basic operating unit system consists of technological natural process,operation process and management process;the process quality of the basic operating unit system depends on the interrelation and interaction among those three sub-processes,and also subjects to the impact of the external disturbance input factors. Finally,the cast-in-situ prestressed concrete continuous box girder construction process is utilized to elaborate the specific application of this theory in the quality management of the railway construction project.
基金Project supported by the National Natural Science Foundation of China (Grand No. 10575055)K. C. Wong Magna Fund in Ningbo University
文摘We investigate a simple evolutionary game model in one dimension. It is found that the system exhibits a discontinuous phase transition from a defection state to a cooperation state when the b payoff of a defector exploiting a cooperator is small. Furthermore, if b is large enough, then the system exhibits two continuous phase transitions between two absorbing states and a coexistence state of cooperation and defection, respectively. The tri-critical point is roughly estimated. Moreover, it is found that the critical behavior of the continuous phase transition with an absorbing state is in the directed percolation universality class.
文摘与传统列控系统相比,全自动无人驾驶运营场景更加复杂多变,潜在的危险及致因具有更强的隐蔽性和复杂性,给运营安全带来了新的挑战。针对以上问题,提出一种STAMP(Systems-Theoretic Accident Model and Process)与模型检验相结合的复杂运营场景安全验证方法。首先,基于STAMP理论构建运营场景分层控制结构模型,辨识潜在的不安全控制行为、分析危险致因和安全约束;其次,定义分层控制结构模型与安全状态机模型间的基本转换规则,基于分层控制结构模型、安全约束和转换规则,构建运营场景安全状态机模型;最后,针对提取的安全约束,利用数据流图建立安全属性验证模型,结合模型检验技术,对运营场景安全状态机模型进行形式化验证。以全自动无人驾驶运营场景中列车自动进站停车为例,对方法进行验证分析。结果表明,当STAMP理论提取的安全约束通过了场景安全状态机模型的验证时,表示在该场景中对应的不安全控制行为没有发生且不导致相应危险。该方法结合系统安全分析与形式化建模验证的优势,降低了运营场景建模的难度,构建的运营场景形式化模型满足系统安全约束,可以作为全自动无人驾驶系统安全设计和安全改进的重要基础。
文摘摩擦力是影响直线伺服系统低速运行与点对点定位精度的主要非线性扰动。广义麦克斯韦(generalized Maxwellslip,GMS)摩擦模型虽然可以准确描述摩擦特性用于前馈补偿,但其存在切换点过渡时振荡的问题,同时易受测量噪声和摩擦参数变化等影响。为此,该文提出基于平滑GMS模型和改进扩张状态观测器(extended state observer,ESO)的复合摩擦补偿策略。首先,引入过渡用双曲正切函数以解决GMS模型中在切换点的反复穿越问题,并给出该模型的离线辨识方法。其次,设计基于模型信息的四阶ESO补偿剩余摩擦力与未知扰动,并引入切比雪夫滤波器整定观测器增益,以降低扰动观测与噪声敏感之间的冲突。为验证所提摩擦补偿策略的有效性,在小型高精度永磁同步直线电机定位平台上进行定位实验。实验结果验证了所提摩擦补偿策略的可行性和有效性。
基金Supported by the National Natural Science Foundation of China （No.60404018） and the State Key Development Program for Basic Research of China （No.2002CB312200）.
文摘A novel control strategy for a continuous stirred tank reactor(CSTR)system,which has the typical characteristic of strongly pronounced nonlinearity,multiple operating points,and a wide operating range,is initiated from the point of hybrid systems.The proposed scheme makes full use of the modeling power of mixed logical dy- namical(MLD)systems to describe the highly nonlinear dynamics and multiple operating points in a unified framework as a hybrid system,and takes advantage of the good control quality of model predictive control(MPC) to design a controller.Thus,this approach avoids oscillation during switching between sub-systems,helps to relieve shaking in transition,and augments the stability robustness of the whole system,and finally achieves optimal(i.e. fast and smooth)transition between operating points.The simulation results demonstrate that the presented ap- proach has a satisfactory performance.
文摘The research hotspot in post-genomic era is from sequence to function. Building genetic regulatory network (GRN) can help to understand the regulatory mechanism between genes and the function of organisms. Probabilistic GRN has been paid more attention recently. This paper discusses the Hidden Markov Model (HMM) approach served as a tool to build GRN. Different genes with similar expression levels are considered as different states during training HMM. The probable regulatory genes of target genes can be found out through the resulting states transition matrix and the determinate regulatory functions can be predicted using nonlinear regression algorithm. The experiments on artificial and real-life datasets show the effectiveness of HMM in building GRN.
文摘The actual world model, the “Standard Model of Cosmology” (SMC), which dates back to the 1950s, no longer corresponds to the latest state of knowledge on the cosmos. By way of example, the assumption made in the SMC that the expansion of the cosmos is continually being reduced due to the effect of the gravitation exerted on all the matter in the universe is now contradicted by recent measurements. The reason for the expansion of cosmic space in accordance with Hubble’s Law is not physically explained by the SMC but merely stated as a fact. Another example is provided by the “dark phenomena”, which make up by far the greatest part of the energy of the cosmos, and exert a dominant influence on its behaviour. In spite of intensive research over the decades to provide answers to these as well as other open issues in cosmology, no satisfactory and plausible answers have hitherto been found. It is indeed time to propose an alternative cosmological world model to the SMC in the light of the latest insights on the universe.
